Reasons for the drop in caribou populations are complicated. There is still some disagreement among scientific and Indigenous experts as to which factors are most important.
Therefore, this section does not try to give definitive answers as to the causes of the herds’ declines, but covers the main theories. It is important to understand that more than one threat operates on a herd at any given time. These cumulative impacts are hard to untangle, and some impacts may be driven by others. For instance, climate change may promote development of parts of a herd’s range which in turn may increase hunting while at the same time insect harassment is increasing, the caribous’ food is changing, and fires are affecting part of the range. Some Indigenous people do not believe the caribou are declining at all. As noted in several documents that contain Indigenous knowledge, some believe that the caribou have moved away, and will return once people are more respectful, or that the caribou have just switched their usual habitat. Data from satellite-collared cows shows that migratory caribou certainly change their migration routes, and have been known to switch herds.